package com.app.shop.config;

import com.fasterxml.jackson.core.JsonGenerator;
import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.JsonSerializer;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.SerializerProvider;
import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Primary;
import org.springframework.http.converter.json.Jackson2ObjectMapperBuilder;

import java.io.IOException;

@Configuration

public class JsonConfig {

    @Bean

    @Primary

    @ConditionalOnMissingBean(ObjectMapper.class)

    public ObjectMapper jacksonObjectMapper(Jackson2ObjectMapperBuilder builder) {

        ObjectMapper objectMapper = builder.createXmlMapper(false).build();

        objectMapper.getSerializerProvider().setNullValueSerializer(new JsonSerializer<Object>() {

            @Override

            public void serialize(Object o, JsonGenerator jsonGenerator, SerializerProvider serializerProvider) throws IOException, JsonProcessingException {

                jsonGenerator.writeString("");//""空字符串或其他字符

            }

        });

        return objectMapper;

    }

}